SESN2 and osteosarcoma: To investigate whether osteosarcoma cells inhibit apoptosis by regulating ER stress to promote autophagy, we treated osteosarcoma cells with chemotherapeutic agents and showed that these treated cells had significant LC3 accumulation compared with that in cells with SESN2 knockdown, and this gap was reduced by 5mM of 4-phenylbutyric acid (4-PBA) (Sigma Aldrich, St.